JP3265449B2 - Distance sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring sensor, and more particularly to detecting a distance of a distance measuring object at any position in a two-dimensional plane projected from a light emitting element. The present invention relates to a distance measuring sensor capable of detecting the directionality of an object to be measured in the form of a projection direction range.

[0002]

2. Description of the Related Art A conventional distance measuring sensor will be described with reference to FIG. First, in FIG. 11, in the conventional distance measuring sensor, the light emitted from the light emitting element 1 is projected toward the distance measuring object 3 after being stopped by the light projecting lens 2,
The semiconductor position detecting element diffused reflection light from above the measuring object 3 due to the light projection by the light receiving lens 4 (P osition S ensiti
ve Photo d etector: hereinafter referred PSD) by condensed to 5, can be detected and measured the distance L to the object 3 from the distance sensor. Since the principle of measuring the distance L is well known for a triangular distance measurement method, the light emitted from the light emitting element 1 is condensed by the light projecting lens 2 and is focused on the distance measurement target 3 here. When the light is projected, reflected by the object to be measured 3, and collected by the light receiving lens 4, a light spot is formed on the PSD 5. And
The position of the light spot on the PSD 5 changes according to the distance L. Since the PSD 5 outputs a signal current corresponding to the position of the light spot, the distance L can be measured by detecting the signal current.

[0003]

In the conventional distance measuring sensor configured as shown in FIG. 11, the distance measuring object 3 is not arranged on the optical axis of the radiated light according to the above measuring principle. Since the emitted light cannot be projected on the distance object 3, the distance measurement object 3 must be arranged on the optical axis of the emitted light for the distance measurement. Therefore, the XY orthogonal two-dimensional plane is used. When the distance measuring object 3 is located at an arbitrary position within the range A that needs to be detected, for example, when the distance measuring object 3 is located at the position 3 'in the code, it is measured on the optical axis of the emitted light. There is a problem that distance measurement cannot be performed because no distance object exists.

Therefore, in order to enable distance measurement of a distance measuring object located in a wide range, for example, as shown in FIG. 12, the light emitted from the light emitting element 1 is stopped down by a light projecting lens as shown in FIG. For example, when the object to be measured is located at the position 8 in the figure, the radiated light 7 in the projected area 6 is projected and reflected on the object 8 to be measured. The distance is measured by focusing the light on the PSD 5 by the light receiving lens 4, but the PSD5 output is not the distance L1 when the object to be measured is at the position 8 in the code but the distance L1 based on the principle of the well-known triangulation method. The output and the measured distance at the virtual position 9 behind the extension line connecting the PSD 5 and the distance measurement target 8 are L
Therefore, there is a problem that distance measurement cannot be performed accurately.

In the case where a plurality of distance measuring sensors 10 are arranged radially so as to project in a light projecting range 6 'so as to cover the distance measuring range A as shown in FIG.
No matter where the distance measuring object 8 is located in the range A, any one of the plurality of ranging sensors 10 is located on the radiation optical path for projecting light. The distance L to the distance measuring object 8 can be detected by a specific distance measuring sensor 10 'projected in the direction in which the distance measuring object 8 is arranged, and the distance measurement is performed. Since it can also be seen that the distance measurement target 8 is within the light projection range A 'of the distance measurement sensor 10' in the direction of the inclination [theta] where the sensor 10 'is disposed, the light emission range A' of the distance measurement sensor 10 ' Although it is possible to detect the direction and the distance, such distance measurement requires a plurality of distance measurement sensors, so it is expensive in terms of cost, and furthermore, the detection by the plurality of distance measurement sensors is difficult. Arranging to cover the required range is for installation There is a problem that becomes enlarged in the shape of a system equipped with a distance measuring sensor is required extra space.

[0006]

Means for Solving the Problems The present invention is, second predetermined range
Multiple light emitting elements on the object to be measured located in the 3D plane
From each of the light emitting elements.
Receiving the reflected light from the object to be measured by the emitted light,
This light reception forms a single semiconductor position detection element.
Of the object to be measured from the position of the light spot to be measured
In a distance measuring sensor of a triangular distance measuring method,
Forward the reflected light to the semiconductor position detecting element in front of the position detecting element.
A single toroidal light-receiving lens that focuses light on the
And the light receiving lens is disposed on the two-dimensional plane.
Reflection with arbitrary incident angle to conductor position detecting element
The above-mentioned problem is solved by focusing light on the semiconductor position detecting element .

Preferably, each of the light emitting elements is individually driven at a predetermined timing, and the semiconductor position detecting element may output a distance measurement signal corresponding to the timing.

[0008]

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a distance measuring sensor according to an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a plan view of a distance measuring sensor according to the present embodiment shown in an orthogonal two-dimensional XY plane, and FIG. 2 is an orthogonal two-dimensional YZ plane.
It is a top view of the distance measuring sensor shown by a plane. The distance measuring sensor shown in these figures has a center point O in an XY plane.
In this embodiment, five light emitting elements 11a to 11e (in FIG. 2, the reference numeral 11 is representatively used) are a plurality of light emitting elements 11a to 11e, each of which is radially arranged along an arc at an equal radial distance from. .)have. With such an arrangement, the light-emitting elements 11a to 11e individually output radiation light Ra to Re (in FIG. 2, this symbol is typically denoted by R). Each of the light emitting elements 11a to 11e is individually in front of each of the light emitting elements 11a to 11e in order to stop down each of the radiated lights Ra to Re along an arc at an equal radial distance from the center point O. (In FIG. 2, this symbol is typically indicated by reference numeral 12.). The detection range of the distance measurement target 13 whose distance is to be detected by the distance measurement sensor of the present embodiment is surrounded by a broken line A by the positional relationship between the light emitting elements 11a to 11e and the light projecting lenses 12a to 12e. Have been. The light emitting elements 11a to 11e are arranged at equal intervals along the arc so that the radiation light Ra to Re from each of the light emitting elements 11a to 11e can cover the entire range A. In addition,
In FIG. 1, only the radiated light Rc from the light emitting element 11c after passing through the light projecting lens 12c is shown to be spread around the optical axis of the radiated light Rc, and the spread range A ″ is hatched. And a state in which the distance measurement target 13 is located within the hatching. A hatched portion indicated by a reference numeral 13 ′ indicates a position when the current distance measurement target 13 has moved to within a radiation range of the radiation Rd from the light emitting element 11 d.

The distance measuring object 13 is located on the optical axis of an arbitrary position range A ″ shown by hatching in the range A, that is, on the optical axis of the radiation Rc from the light emitting element 11c. The reflected light Rc ′ based on the radiated light Rc from the distance measuring object 13 (the radiated light is typically indicated by a symbol R in FIG. 2, but is the radiated light from each of the light emitting elements 11a to 11e). Among them, only the emitted light Rc is reflected, so that the reflected light is reflected light Rc ′ by the emitted light Rc).
5, the PSD 15 forms a light spot by the reflected light Rc ′. In the PSD 15, a distance measurement signal is output in accordance with the formation position of the light spot formed based on the light emitted from the light emitting element 11c. In this case, the light spot corresponds to each of the light emitting elements 11a to 11e. From each radiation Ra ~
Re from any output timing of each light emitting element 1
Since it is known from the contents described later with reference to FIGS. 3 and 4 whether or not the light spot is formed based on the radiated lights Ra to Re from the light sources 1a to 11e, the distance is measured based on the principle of the triangulation. The distance L to the object 13 can be detected. Therefore, even if the distance measuring object 13 is located in any of the ranges A, the radiation light Ra to Re is emitted from each of the light emitting elements 11a to 11e, and the distance measuring object 13
A corresponding light spot is formed on the PSD 15 by the reflected light from the object, so that the number of the PSDs 15 is one. The distance to the object 13 can be detected. In addition, the radiation light Ra to R from each of the light emitting elements 11a to 11e with respect to the distance measurement target 13 within this range A.
e, and the reflected light is incident on the PSD 15, so that it is possible to determine the position within the range A where the distance measurement target 13 is located. In addition, since the emission light output timing is set so that the light emitting elements 11a to 11e sequentially emit the emission light Ra to Re as described later, first, the driving of the light emitting element 11a is started to emit light. Element 11
The driving of the first cycle is completed by the driving of e, and at this stage, when the object to be measured is at the position 13 in the code, it can be detected by the emitted light Rc of the light emitting element 11c. When the object is located at the position 13 ', it can be detected by the emitted light Rd of the light emitting element 11d. Therefore, it is found that the distance to the object to be measured and the object to be measured are located in the range A. In addition, the direction in which the object to be measured moves, that is, the direction in which the object moves from the position 13 to the position 13 'is determined. As described above, in a device using a sensor according to the moving direction of the object to be measured, the range of application of the control can be expanded.

Next, the timing of the emitted light output of each of the light emitting elements 11a to 11e and a drive circuit for driving the light emitting elements 11a to 11e for obtaining the timing will be described with reference to FIGS. . FIG.
The low levels indicated by a to e are active levels, and indicate time-division driving pulses 11a 'to 11e' for driving the light emitting elements 11a to 11e, respectively. The light emitting elements 11a to 11e are driven by these driving pulses. It is driven to output radiation light Ra to Re, respectively. And
FIG. 3F shows the ranging signal Vo of the PSD 15. FIG.
At f, the ranging signal 16 is based on the reflected light on the PSD 15 due to the emitted light Ra of the light emitting element 11a.
Is based on the reflected light from the light emitting element 11b to the PSD 15 due to the emitted light Rb, and the distance measurement signal 18 is
This is due to the reflected light to the PSD 15 due to the emitted light Rc. In this way, the ranging signal from the PSD 15 based on the emitted light Ra to Re of each of the light emitting elements 11a to 11e is output in a time-division manner. In FIG. 4, the drive pulses 11 a ′ to 11 e ′ are output from the device control unit 40, and these drive pulses 11 a ′ to 11 e ′ are given to the distance measurement sensor 41. The distance measuring sensor 41 includes a driving circuit 42 to which the driving pulses 11a 'to 11e' are input, the light emitting elements 11a to 11e, the light projecting lenses 12a to 12e, the light receiving lens 14, the PSD 15
And a signal processing circuit 43 for processing the ranging signal Vo from the PSD 15. The device control unit 40 is configured as shown in FIGS.
The drive pulses 11a'-11 at the timing indicated by e
e ′, and the drive circuit 42 sequentially drives the light emitting elements 11a to 11e to emit light in response to the input of these drive pulses. In this way, if the distance measurement target 13 shown in FIGS. 1 and 2 is located on the optical axis of the light emitting element 11c, for example, the PSD 15 obtained based on the radiation Rc from the light emitting element 11c. Since the distance measurement signal 18 indicates the distance L to the distance measurement target 13, the data of the distance L and the light emitting element 11c set in advance by the design value are used.
, The directionality of the distance measurement target 13 can be simultaneously determined based on the range of the projection direction of the radiation light Rc.

Next, XY2 of a wide range A shown in FIG.
In order to detect the directionality and the distance of the distance measuring object 13 located in the three-dimensional plane with one PSD 15, FIG.
The optical lens 19 (corresponding to the light receiving lens 14) and the PSD 20 (PSD) are arranged in a three-dimensional plane of X, Y, and Z as shown by.
15 (corresponding to 15). FIG. 5A shows the positional relationship between the optical lens 19 and the PSD 20 when viewed from the ZX plane. The Z-axis longitudinal direction of the PSD 20 and the X-axis longitudinal direction of the optical lens 19 are above the Y-axis of the PSD 20. The positions are orthogonal to each other. FIG. 5B shows the positional relationship as viewed from the XY plane, and FIG. 5C shows the positional relationship as viewed from the YZ plane. As is clear from this positional relationship, the PSD
With respect to the reflected light that is reflected from the object 13 and is incident on the object 20, the optical lens 19 is used to stop in the Z-axis direction. Although the position accuracy of the light spot on the PSD 20 is increased by making the width narrower, the optical lens 19 does not stop the aperture in the X-axis direction.

In such a positional relationship, the reflected light 21 from the object to be measured enters through the optical lens 19 parallel to the PSD 20 on the XY orthogonal two-dimensional plane as shown in FIG. Then, since the focal length 21f of the reflected light 21 is set on the PSD 20, the reflected light 21 forms an image on a plane including the PSD 20. This image is shown in FIG. The image 23 shown in FIG. 6B extends in the X-axis direction across the PSD 20, and an image portion on the PSD 20 becomes a light spot. In this case, since the reflected light 21 is converged and condensed in the Z direction by the optical lens 19, the line width of the light spot on the PSD 20 is small.

However, the problem here is that the reflected light projected radially, reflected by the object to be measured and incident on the PSD 20 has an incident angle θ with respect to the Y axis. For example, in FIG. 6A, for the reflected light 22 entering at an angle θ compared to the reflected light 21, the distance from the stop surface of the optical lens 19 to the PSD 20 is 22 f, which is compared with the focal length 21 f of the reflected light 21. As a result, a relationship of 21f <22f results. In this case, since the focal length of the optical lens 19 is only the focal length 21f from the design point of view, the incident light 22 is focused and condensed at a position above the PSD 20 on the Y axis. As shown in FIG. 6B, an image 24 is formed by hatching to the right due to the reflected light 22. Since the image 24 is not focused, the line width in the Z-axis direction is thicker than the image 23,
The line width of the light spot on the surface 20 in the Z direction becomes large, and a distance measurement error is likely to occur.

In order to solve such a problem, it is proposed in this embodiment to use a toroidal optical lens 25 having a semicircular cross section as shown in FIG. FIG. 7a is shown in FIG. 6a, FIG.
c is the optical lens 25 and PSD corresponding to FIG.
It is a positional relationship with 20. Here, this optical lens 25
7d shows that the cross section taken along the line AA ′ and the cross section taken along the line BB ′ of FIG. 7b have the same shape. When the optical lens 25 having such a structure is used, FIG.
As shown in FIG. 8A corresponding to FIG. 8A, the reflected light 26 incident parallel to the PSD 20 in the Y-axis direction
With respect to the reflected light 27 incident on the D20 at an angle θ in the Y-axis direction, each of the reflected lights 26, 27 has a focal length 26f, 27f at which the focal length 26f, 27f is focused on the PSD 20; It is configured to be.

In the case where such an optical lens 25 is used, as shown in FIG. 8B corresponding to FIG.
Also has a narrow line width in the Z-axis direction, so that PS
The light spot by the reflected lights 26 and 27 on D25 also has a narrow line width, and the distance measurement accuracy is greatly improved.

In FIG. 7, the toroidal optical lens 25 is used. However, as shown in FIG. 9, a plurality of spherical lenses 30 each having an aperture in both the X and Z directions are illustrated. 8 are arranged at regular intervals corresponding to the arc surfaces of the optical lenses 25, the spherical lenses 30 have the same focal length f, so that the reflected light passing through each spherical lens 30 is reflected on the PSD 20. It is focused and condensed, and the ranging accuracy can be improved.

The outer shape of the distance measuring sensor according to the present embodiment will be described with reference to FIG. This distance measuring sensor has a projecting portion having a lower portion projecting forward, the front surface of the projecting portion being a stepped arcuate surface, and a light projecting lens 12a on each surface.
12e are provided, and the respective light projecting lenses 12a to 12e
The light-emitting elements 11a to 11e not shown in the figure are provided in the inside, the light receiving lens 14 is provided in the upper front surface, and the PS not shown in the figure corresponding to the light receiving lens 14 is provided.
D20 has a deployed shape.

In the present invention, the light emitting elements 11a to 11a
Although 11e is arranged on an arc having the same radial distance from the center point O, it is sufficient that the wide area A can be individually covered, and it is not necessarily required to be arranged on the same radial distance, and the radiation directions of the respective radiated lights Ra to Re are provided. It is good to be arranged toward.

In the present invention, the light emitting elements 11a to 11a
11e are equidistant from each other, but do not necessarily have to be equidistant. For example, the distance between the light emitting elements arranged from the center to the left and right may be narrowed or widened.

In the present invention, the light projecting lens 12a
To 12e are not necessarily essential, and the radiation light Ra to
If Re is emitted, the light projection lens may be omitted.

[0022]

As described above, according to the present invention, the light emitted from the light emitting element is projected on the object to be measured, and the reflected light reflected by the object is received by the PSD. In a distance measuring sensor of a triangular distance measuring method for detecting a position of a distance measuring object from a position of a light spot formed on a PSD by this light reception, a distance measuring object located in a two-dimensional plane within a predetermined range is detected. In order to perform at least distance measurement, the light-emitting elements of the light-emitting elements are so arranged that the light emitted from each of the light-emitting elements can individually emit the light toward a distance-measuring object located at an arbitrary position in the predetermined range in the two-dimensional plane. Since a plurality of light emitting elements are arranged and a single PSD is arranged at a position where the reflected light from the object to be measured by the light emitted from each light emitting element can be received and a distance measurement signal can be output, Distance measurement target at any position within the predetermined range About it can be accurately the distance measurement also.

When each light emitting element is individually driven at a predetermined timing, and the PSD outputs a ranging signal corresponding to the timing, the PSD detects a moving direction of the object to be measured from the ranging signals. it can.

Further, a light-receiving lens for condensing the reflected light on the PSD is disposed in front of the PSD, and the light-receiving lens is adapted to reflect reflected light entering the PSD at an arbitrary incident angle on a two-dimensional plane. On the other hand, in the case of focusing on the PSD, the line width of the light spot on the PSD based on the reflected light at any incident angle can be reduced.
The position accuracy of the light spot on the PSD is improved, and the distance measurement accuracy can be improved.

[Brief description of the drawings]

FIG. 1 is an XY diagram of a distance measuring sensor according to an embodiment of the present invention.
It is a figure showing composition seen from a plane.

FIG. 2 is a diagram showing a configuration of the distance measuring sensor as viewed from a YZ plane.

FIG. 3 is a diagram showing drive pulses for driving a plurality of light emitting elements of the distance measuring sensor.

FIG. 4 is a circuit and a PSD for processing the driving pulse of FIG. 3;
FIG. 3 is a circuit diagram showing a circuit for processing a ranging signal of FIG.

5A and 5B are diagrams illustrating a positional relationship between an optical lens serving as a light receiving lens and a PSD, wherein FIG. 5A illustrates a positional relationship viewed from a ZY plane, and FIG. 5B illustrates a positional relationship viewed from a YX plane. (C) shows the positional relationship as viewed from the YZ plane.

6A and 6B are diagrams for explaining an incident angle of radiated light through the optical lens of FIG. 5 and formation of a light spot on a PSD by the radiated light. FIG. FIG. 3B shows the positional relationship between the light receiving lens and the PSD on the ZX plane.

7A and 7B are diagrams showing a positional relationship between an optical lens as another light receiving lens and a PSD, wherein FIG. 7A shows a positional relationship as viewed from a ZY plane, and FIG. 7B shows a positional relationship as viewed from a YX plane. (C) shows the positional relationship viewed from the YZ plane,
(D) is a sectional view of the optical lens taken along the line AA 'and the line BB' of (a).

8A and 8B are diagrams for explaining an incident angle of emitted light through the optical lens of FIG. 7 and formation of a light spot on a PSD by the emitted light, and FIG. 8A illustrates an optical lens on a YX plane; FIG. 3B shows the positional relationship between the light receiving lens and the PSD on the ZX plane.

FIG. 9 is a view showing another modification of the optical lens.

FIG. 10 is a diagram illustrating an appearance of a distance measuring sensor according to the embodiment of the present invention.

FIG. 11 is a diagram showing a configuration of a conventional distance measuring sensor.

FIG. 12 is a diagram showing a configuration of another conventional distance measuring sensor.

FIG. 13 is a diagram showing a configuration of still another conventional distance measuring sensor.

[Explanation of symbols]

 11a to 11e Optical element 12a to 12e Light projecting lens 13, 13 'Distance measuring object 14 Light receiving lens 15 Semiconductor position detecting element (PSD) Ra to Re radiation light Rc' reflected light

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) G01C 3/00-3/32 G01B 11/00-11/30

Claims (2)

(57) [Claims] 1. A distance measuring device located in a two-dimensional plane within a predetermined range.
Emitting emitted light from multiple light-emitting elements individually to the object,
The distance measuring pair by radiation light from each of the light emitting elements
The reflected light from the elephant is received, and the received light
From the position of the light spot formed on the conductor position detection element
A triangulation-based distance measuring system for detecting the position of the object to be measured.
The reflected light in front of the semiconductor position detecting element.
A single toroidal receiver that focuses on the body position detector
An optical lens is provided, and the light receiving lens is
Any angle of incidence on the surface with respect to the semiconductor position detecting element
Is reflected on the semiconductor position detecting element for reflected light having
A distance measuring sensor characterized by focusing . 2. The distance measuring sensor according to claim 1, wherein each of the light emitting elements is individually driven at a predetermined timing, and the semiconductor position detecting element outputs a distance measuring signal corresponding to the timing. .